<!DOCTYPE html>
<html lang="zh-hans">
<head>
    <meta charset="UTF-8">
    <title>查查现在几点了</title>
</head>
<body>
    <button>点我显示当前时间</button>
    <div class="显示时间区域"></div>

    <script src="demo9.js"></script>
</body>
</html>